The invention relates to a pressure-compensated solenoid valve for controlling the passage of a connecting line between a high-pressure side and a low-pressure side of a fuel injection nozzle.
Solenoid valves of this kind are generally intended for use in internal combustion engines with high engine speeds and with highly stressable high-pressure connections between fuel injection pumps and injection nozzles. Extremely rapid switching processes with a minimal application of energy can be carried out with these solenoid valves. The use of such valves is shown, for example, in application Ser. No. 08/342,606 assigned to the assignee of the present invention.
DE 37 32 553 A1 discloses a solenoid valve of this type in which a step-shaped control piston can be displaced in a step-shaped guide bore in a multi-part valve housing. The control piston is provided with an annular recess between the piston portions of different diameters, the enlarged piston portion having a tapered portion axially adjacent the recess in order to form a sealing edge. Above the sealing edge, a high-pressure line opens radially into an annular space which is in communication, only in the open position of the control slide, with a low-pressure line which opens radially into an annular recess between the two piston portions. In addition, an actuation rod is screwed into the control piston which is of hollow design and a flat armature is attached to the free end of the actuation rod.
It is the object of the invention to provide a solenoid valve of this type with pressure compensation and to do this in a simple fashion without adversely affecting safe seating of the valve in spite of the high pressures effective in the valve.